Plants use photosynthesis to convert water and carbon dioxide to create organic compounds such as cellulose or glucose. It is well-established that artificial lights can be substituted for natural sunlight. In addition to conventional incandescent lights, High Intensity Discharge (HID) lamps, such as Metal Halide (MH) and High Pressure Sodium (HPS), have been used to grow plants. Fluorescent lamps are another example of artificial illumination used to grow plants. Some plant growers desire the ability to control the amount of light provided to the plant. HID and fluorescent lamps require an electronic ballast for operation, which makes controlling the light intensity a challenge.
Light emitting diodes (LEDs) are new a lighting technology in the grow light industry. LEDs emit light at specific wavelength bands depending upon the type of diode. Because of this narrow wavelength band a white LED is actually comprised of a mix of different color LEDs to create the white light. The intensity of an LED may be controlled as well. Therefore LEDs may be dimmed.
Like any other industry, the agricultural industry seeks to increase production and lower operating costs of its products. Generally, plants exposed to more blue light tend to grow stouter and with broader leads. Plants exposed to more red light tend to grow faster and taller but with thinner stems and smaller leaves.
Research has determined that the 660 nm wavelength is crucial to trigger flowering in a plant. In some plant species the 660 nm wavelength must not be present longer than 12 hours per day in order for the plant to flower and to continue to flower. The solution has been to provide illumination for less than 12 hours per day.
An exemplary embodiment may overcome these problems and provide a grow light where the 660 nm frequency band may be turned off.